pope benedict xvi was born joseph ratzinger in 1927 in germany. he became a cardinal in 1977 and was chief theological adviser to pope john paul ii. following the death of john paul he was elected pope back in 2005. he was 78, the oldest person to become pope in almost 300 years. little has been said publicly about his health, which made his resignation even more surprising since he said his strength has deteriorated recently. let's get some more now on the pope's health. our chief medical correspondent, dr. sanjay gupta, is joining us. sanjay, what do we know about the pope's health as of late? >> well, you know, not much that's new here, wolf. and i think that's part of the reason this came as a surprise to so many people. certainly we know his age, 85 years old, and as a physician there's all sorts of different things that you certainly worry about. cardiovascular disease, diabetes, cancer, stroke. he had a hemorrhage in his brain they think back in 1991 that may have been due to a stroke. but a long time ago, and there was no evidence of anyth